I guess thatr the Tamron wins hands down for video use over the canon mk2 due to the VC?

Only if you use handheld static video, but for most professional applications a body stabilization gear is used which prevents the typical IS/VC "skip" when moving around.

+1When handheld the VC is better than my Canon 70-200 f/2.8 L IS II ... but once you set it on a tripod and shoot, Canon lenses produce superior clarity, sharpness & colors. The 24-70 f/2.8 VC is a great lens for its price - basically value for money. But if you want tack sharp image across the image, get Canon 24-70 f/2.8 L II